Atomic Models and Lithium Atom

Dalton’s Model

• Atoms are tiny, solid, indivisible balls
• Atoms combine in whole number amounts

Thomson’s Model

• Atoms contain tiny, negatively charged particles called electrons
• Atoms are positively charged with electrons stuck inside

Rutherford’s Model

• Most of an atom is empty space
• The center has a small, dense core (nucleus) with a positive charge
• Electrons move around the nucleus

Bohr’s Model

• Electrons orbit the nucleus in certain paths or energy levels

Lithium Atom

• Protons: positively charged particles in the nucleus
• Neutrons: neutral particles in the nucleus
• Electrons: negatively charged particles orbiting the nucleus

Atomic Number and Mass

• The atomic number equals the number of protons in an atom
• The number of electrons equals the number of protons
• The total particles in the nucleus equal the atomic mass rounded off
• The number of neutrons equals the total particles minus the protons

Ion Charge of a Lithium Ion

• A lithium ion loses an electron
• Charge: 3 positive protons – 1 negative electron = 2+ charge

Reactions and Charges

• Alkali metals give 1 electron, so their ion charge is 1+
• Alkaline earth metals give 2 electrons, so their ion charge is 2+
• Halogens gain 1 electron, so their ion charge is 1-
• Noble gases don’t react, and their charge is 0

WHMIS

• Workplace Hazardous Materials Information System
• Warns about dangers of materials

MSDS

• Material Safety Data Sheet

Physical Properties of Matter

• Matter is anything that has mass and takes up space
• Physical properties describe what matter looks like or how it behaves without changing its chemical structure

Examples of Physical Properties

• Appearance
  • Color, texture, luster
• State
  • Solid, liquid, gas
• Boiling and freezing points
• Density
• Malleability
• Ductility

Types of Properties

• Intensive properties don’t depend on the amount
• Extensive properties depend on the amount

Chemical Properties

• Can only be found by changing a substance into something else

Physical Changes

• Change in the shape, size, or form of a substance, but it stays the same substance
• Examples:
  • Water turning into ice
  • Dissolving salt in water
  • Breaking a rock
  • Tearing a piece of paper

Chemical Changes

• A substance reacts and forms a completely new substance
• Examples:
  • Baking bread
  • Fireworks exploding
  • Burning wood
  • Cooking an egg

How to Tell the Difference Between Physical and Chemical Changes

• Physical changes are often reversible
• Chemical changes are usually irreversible

Bohr Models

• Used to predict reactivity in elements

Valence Electrons

• Valence electrons are electrons on the last energy level

Drawing Bohr Models

• Draw nucleus
• Write number of neutrons and protons
• Draw energy levels
• Draw electrons in energy levels

Rules for Energy Levels

• Level 1 can hold a maximum of 2 electrons
• Level 2 can hold a maximum of 8 electrons
• Level 3 can hold a maximum of 8 electrons
• Level 4 can hold a maximum of 32 electrons
• Fill one level before going onto the next

Ionic Compounds

• Metal atoms want to give away electrons
• Nonmetal atoms want to take electrons
• Metal and nonmetal atoms trade electrons
• Metal atom becomes a positive ion
• Nonmetal atom becomes a negative ion
• Ions stick together and form a solid at room temperature
• Brittle and break easily
• Conductors of electricity when heated or dissolved in water

Prefixes for Number of Atoms

• Mono: 1
• Di: 2
• Tri: 3
• Tetra: 4
• Penta: 5
• Hexa: 6
• Hepta: 7
• Octa: 8
• Nona: 9
• Deca: 10

Example

• Diphosphorus pentoxide
  • Two phosphorus atoms
  • Five oxygen atoms
  • Chemical formula: P₂O₅

Writing Formulas for Molecular Compounds

• Not expected to write formulas for the state of the compound at room temperature

Explore the different atomic models proposed by Dalton, Thomson, Rutherford, and Bohr in this quiz. Test your knowledge on the structure of a lithium atom, including protons, neutrons, and electrons, as well as how atomic number and mass are calculated. Perfect for high school chemistry students!